Revenue - Schedule of Expected Revenue to be Recognized for Existing IRU Contracts (Details) $ in Millions	Sep. 30, 2021 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue to be recognized	$ 138.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue to be recognized	$ 0.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue to be recognized	$ 4.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue to be recognized	$ 6.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue to be recognized	$ 7.9
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue to be recognized	$ 7.9
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue to be recognized	$ 111.3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130556-203045

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Period in which remaining performance obligation is expected to be recognized as revenue, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130556-203045

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